Association of social determinants of health and age at menopause: NHANES 1999-2018 observational study.

Study question: Do social determinants of health (SDoH) influence the age at menopause among women?

Summary answer: In our study, adverse SDoH, particularly family low income-to-poverty ratio (PIR), low education level, and the marital status of being widowed, are associated with earlier age at menopause.

What is known already: Some prior studies have considered certain SDoH variables (such as educational attainment and marital status) as potential factors influencing age at menopause, but systematic evidence clearly defining the relationship between multidimensional SDoH and menopausal age remains lacking.

Study design size duration: This cross-sectional analysis included 6083 naturally menopausal women from 10 cycles (1999-2018) of the United States National Health and Nutrition Examination Survey (NHANES) and excluded cases of surgical menopause.

Participants/materials setting methods: The participants were derived from a nationally representative sample of the NHANES 1999-2018 in the USA. Eight SDoH variables were assessed: employment, PIR, food security, education, healthcare access, health insurance, housing stability, and marital status. Age at menopause was determined by self-reported last menstrual period among women with natural menopause. This study constructed weighted multivariate linear regression models and weighted quantile sum (WQS) analyses and calculated regression coefficients (β) and their 95% CIs. Subgroup analyses and sensitivity analyses were used to verify the robustness of our findings.

Main results and the role of chance: After adjusting for relevant confounding factors, adverse PIR, education level, and marital status (such as being widowed) were significantly associated with earlier age at menopause. Specifically, compared to women with a PIR ≥500%, women with a PIR between 100% and 300% or PIR ≤100% had an earlier age at menopause by 0.877 years (95% CI: -1.526, -0.229, P = 0.008) and 1.296 years (95% CI: -2.105, -0.487, P = 0.002), respectively. Additionally, compared to women with an educational level of college or above, women with a high school education or less than a high school education had earlier age at menopause by 1.262 years (High school: 95% CI = -1.914, -0.609, P < 0.001) and 1.403 years (Less than high school: 95% CI = -2.062, -0.743, P < 0.001), respectively. Compared to women who were married or living with a partner, widowed women had earlier age at menopause by 1.363 years (95% CI = -1.887, -0.839, P < 0.001). Analysis using a WQS regression model based on decile categorization demonstrated that each 1-unit increase in the composite exposure index of adverse SDoH factors was associated with 3.302 years earlier age at menopause in women (95% CI = -4.129, -2.476, P < 0.001). The PIR contributed most substantially to the inverse association between SDoH and age at menopause.

Limitations reasons for caution: The cross-sectional design limits causal inference. Unmeasured confounders (e.g. parity, previous hormone use, chemical exposures) and recall bias may persist despite sensitivity analyses.

Wider implications of the findings: These findings substantiate the implementation of integrated multidimensional interventions targeting economic stability, housing security, employment support, and healthcare access, which would likely yield substantially greater benefits than single-dimensional policy adjustments. Moreover, material deprivation factors may exert profoundly stronger effects on reproductive aging than previously thought.

Study funding/competing interests: This work was supported by the National Key Research and Development Program of China (2023YFC2705700), the Interdisciplinary Innovative Talents Foundation from Renmin Hospital of Wuhan University (JCRCYG-2022-009), and the National Natural Science Foundation of China (72474005). All authors declare no competing interests.

Trial registration number: N/A.